To measure the absorption of heme and non-heme iron in women, pregnant and non-pregnant women will consume a standardized meal of pork (intrinsically labeled with 58Fe) and a second meal of non-heme 57Fe (as ferrous sulfate). Two weeks after ingesting these test meals, a blood sample will be collected from each women and the amount of heme (58Fe) and non-heme (57Fe) iron incorporated into red blood cells will be measured with magnetic sector thermal ionization mass spectrometry. Cord blood samples and placental tissue will be obtained at delivery to measure how these two forms of dietary iron were transferred across the placenta to the fetus. Maternal and neonatal iron status and placental proteins involved in iron transport will also be measured. Data from this study will provide information that aims to improve human health by better understanding the iron requirements of a population at high risk of iron deficiency.